Ship project history:
Satsuma and Aki were to have been the
first Japanese all-big-gun battleships, but 254mm guns had to be substituted for
single 305mm due to shortages in Japan. Thus the planned 12-305/45 (4x2, 4x1)
were replaced by 4 305mm and 12 254mm (6x2). Both units were ordered from the
two main Navy yards (Yokosuka and Kure) late in 1904, but Aki could not
be laid down until her slip was vacated by the armoured cruiser Tsukuba.
The delay allowed the Japanese Navy to decide to fit her with turbines (which
were Curtis units built by the Fore River Yd in the United States), and to
replace her 120mm secondary battery with 152mm guns. Aki also differed
visually from her near sister. She had three unequally spaced funnels (the third
further apart than the other two). By way of contrast, the next ship, the
Kawachi, had her last two funnels closer together.

Satsuma made 18.95kts on 18,507ihp on trials; Aki 20.25kts on
27,740shp.

Ship protection:
Thickness of main belt was 229mm between main gun barbettes decreasing to
127mm outside barbettes and to 102mm near ship ends. There was
upper belt between main belt and casemate deck. Its thickness was 203mm between
main gun barbettes decreasing fwd from fore barbette. Casemates were protected
by 152mm armor. 51mm main deck connected with lower
edge of main belt by 76mm slopes. 12`` turrets had 305mm faces and
203mm sides. CT had 305mm sides and 102mm roof.